Monthly Archives: February 2015

Childhood predictors of adult outcomes

Two papers in The Economic Journal November 2014 deal with how childhood information may predict adult outcomes.

Frijters, Johnston and Shields consider the question Does Childhood Predict Adult Life Satisfaction? Using repeated surveys of people born in the UK in 1958, they are able to explain only 7 % of people’s adult life satisfaction with a very wide range of family and childhood variables. Interestingly, exploiting the panel dimension, they estimate that around 40 % of adult life satisfaction is a trait (i.e. fixed), so it is surprising that their first number is so low. It is as if type of childhood almost does not matter. Education and wages are predicted much better.

I do not know if information on time preferences would have helped, but Golsteyn, Grönqvist and Lindahl at least claim that Adolescent Time Preferences Predict Lifetime Outcomes in their article in the same issue. They find that Swedes who were future-oriented (had low discount rates) as children went on to obtain more education, better grades, higher incomes, and better health (obesity and mortality) as adults than their more impatient peers. The authors are admirably clear that they are not estimating causal effects.

Review: Intelligence: A Very Short Introduction

Since I am doing some work using intelligence test data, I wanted to read something introductory material on that topic. Enter Intelligence: A Very Short Introduction (2001) by Ian J. Deary. I found this a useful introduction to how psychologists/psychometricians have thought about these things. What I was really after was the foundational stuff in chapter 1, and that is what I will focus on here. (Though chapter 6 on the Flynn effect is also solid, and taught me that American SAT scores have been declining in the same period as IQ scores have been rising.)

Deary takes the test collection called Wechsler Adult Intelligence Scale III as a starting point. WAIS-III consists of 13 different tests, and strikingly,

“every single one of those 13 tests in the WAIS-III  has a positive correlation with every other one. People who are better at any one test tend to be better at all of the others. There are 78 correlations when we look at all the pairings among the 13 tests. Every single correlation is positive – a good score on one of the tests tends to bring with it a good score on the others. There are no tests unrelated to any other one, i.e. there are noe near-to-zero correlations. There are no tests that are negatively related with other ones. Even the lowest correlation between any two tests is still a modest 0.3 (between picture completion and digit span). […]

The first substantial fact, then, is that all of these different tests show positive associations – people good at one tend to be good at all of the others. […]

The second important fact is that some sub-groups of tests in the WAIS-III collection associate higher among themselves than with others. For example, the tests of vocabulary, information, similarities, and comprehension all have especially high associations with each other. So, although they relate quite strongly to every test in the WAIS-III collection, they form a little pool of tests that are especially highly related among themselves. The same thing occurs with digit span, arithmetic, and letter-number sequencing. They relate positively with all of the other tests in the collection, but they relate especially highly with each other (pp. 7-8).”

In the WAIS-II tests, there are four groups of tests that correlate particularly strongly (called “group factors”), labelled: Verbal comprehension, Perceptual organization, Working memory, and Processing speed, ref. the figure below (p. 3). Inline image 2

Positive correlations between the four group factors are high. This has often been taken to imply that the skills required to do well on each have some common source, which has traditionally been called g (“general factor”). Strictly speaking, the fact that the different test scores are positively correlated does not imply that they have something in common or that “g” corresponds to anything real. Deary is at one point fairly clear about this, writing: “The rectangles in Figure 1 are actual mental tests – the 13 sub-tests – that make up the Wechsler collection. The four circles that represent the ‘group factors’ and the circle that contains g are optimal ways of representing the statistical associations among the tests contained in the rectangles. The things in the circles, the specific/group factor abilities and ‘g’, do not equate to things in the human mind – they are not bits of the brain (p. 11).”

Though he muddles it somewhat when continuing with “The names we pencil into the circles are our common-sense guesses about what seems to be common to the sub-groups of tests that associate closely. The circles themselves emerged from the statistical procedures and the data, not from intuition about the tests’ similarities, but the labels we give the circles have to be decided by common sense (p.11),” and later much more by going on to treat ‘g’ as a valid stand-alone explanatory concept, and writing e.g. “We already know from Chapter 1 that there is general ability and there are […] specific types of mental ability (p. 85).”

Nevertheless, the book seems to be a good exposition of intelligence testing and how psychologists have viewed and continue to view the results of these tests.



Monthly book roundup – 2015 January

Books finished in January:
(Warning: reviews are unpolished and quickly written.)

Augustus (1972) by John Williams. The story of Gaius Octavius, the founder of the Roman Empire and the First Roman Emperor Augustus, told through (fictional) letters between Augustus and his friends, enemies and acquaintances. From when his maternal great-uncle Julius Caesar was assasinated and Octavius made his heir only 18 years old, through his 41 year reign, until he died an old man. The history comes alive through Williams’ fiction. Recommended. (On Christopher Blattman’s suggestion.)

Station Eleven: A novel (2014) by Emily St. John Mandel. Ok. Living before and after a deadly global flu.

Infinite Jest (1996) by David Foster Wallace. Some great passages, particularly about drug use, but overall way too long and sprawling. Maybe that is a postmodernist point, but that in any case makes me lose interest. Quit after about 1/6.

The History of White People (2011) by Nell Irwin Painter. Interesting parts, like about how there used to be hard within-European white fronts that are now much less pronounced, and president Theodore Roosevelt’s worries about racial decay and writings about positive eugenics (boosting fertility), but overall I found the book too long and slow.

Age of Ambition: Chasing Fortune, Truth, and Faith in the New China (2014) by Evan Osnos.
Good book about how times are changing in China, well told through various characters. But I am not that interested so stopped midway through.
Beijing changed very much.
Incredible story of Justin Yifu Lin from Taiwan, who defected and swam to China, left family, became economist, got Chicago phd, and became Chief Economist of the World Bank.
Ref to Norwegian sinologist Mette Hansgård Hansen who saw teachers imparting individualism.
Story of girl Gung who went to school. Created dating site.
Funny about Chinese tourists in Europe.
Truth chapter-about the propaganda department. Propaganda important for Mao. We hear about the judgement of Mao having been 77% correct and 30% wrong. Under Deng: Studied western PR and spin policies to improve propaganda. Censorship, no mention of Tiananmen e.g. Freedom of speech and the press guaranteed in the constitution, “but regulations gave government broad powers to imprison editors and writers for “harming national interests” and other offenses (p. 122)”. Parallel realities-public and real.
Recommended for those interested in China.

Ratings and old books are in the library.